The present invention relates generally to web services and more particularly, to a method and system for creating a dynamic Open Grid Service Infrastructure (OGSI) service proxy framework using runtime introspection on an OGSI service.
Web services are defined as independently operated applications that are implemented over the Internet and which allow disparate systems to interact via common specifications and protocols. Existing Web services are still in their infancy stage. To date, there is no universally-accepted standard that would allow business enterprises to realize the full potential of Web services.
One type of Web service that is breaking ground is grid computing which involves bringing together numbers of heterogeneous computing devices resulting in a virtual organization (VO) whereby processing cycles and other resources can be shared for implementing complex functions.
The Open Grid Services Architecture (OGSA) is a grid system architecture based on an integration of Grid and Web services concepts and technologies. It includes a community-based set of services and software libraries for providing security, information infrastructure, resource management, data management, communication, fault detection, and portability functions. OGSA utilizes Web Services Description Language (WSDL), an XML-formatted language, to describe a Web service's capabilities for exchanging messages. OGSA includes WSDL interfaces, conventions, and service bindings that define the components required for creating complex distributed systems, such as lifetime management, change management, and notification, as well as for supporting security features. Utilizing WSDL, the OGSA architecture defines extensions to web services that specify properties for grid applications. These extensions, and their definitions in the OGSA specification, seek to provide a standard for technology such as portType relationships and serviceData in order to ensure interoperability among running grid services.
The OGSI (Open Grid Service Infrastructure) services exposes service specific meta-data and state data (e.g., relating to the schema of the database) through the OGSI service data framework and provides a common interface (FindServiceData) for accessing these service data through a ‘GridService’ interface. The meta-data about a service is exposed as service data elements through the service's mandatory interface called GridService portType. The information exposed through this interface is helpful for service introspection and semantic inferences on a particular service. The OGSA specification suggests using these introspection mechanisms for better coherence with the service implementation and for the correct runtime behavior rather than binding to some predefined and static definitions (including predefined WSDL definitions and service data element definitions about service). This assumption is based on the assumed GRID service behavior where a service can dynamically add service data elements and change its Grid service reference (GSR) information during its existence. Unlike a Grid service handle (GSH), which is invariant, the GSR(s) for a Grid service instance can change over that service's lifetime. When factories are used to create a new instance of a grid service, the factory returns the identity of the new instantiated service. This identity is composed of two parts, a GSH and a GSR. A GSH is guaranteed to reference the grid service indefinitely, while a GSR can change within the grid services lifetime.
The irony of OGSA is that, although meant to address a dynamic, distributed, on demand, ‘utility’ style of computing (i.e., grid computing), no provision is made for dynamically employing service provided meta-data and introspection capabilities of the service, thus maximizing flexibility of the client by eliminating a need for any pre-assumed programming artifacts, and at the same time, being in sync with the service provided information model and capabilities.
What is needed, therefore, is a way to improve the web service by defining a grid service that can enable a dynamic client side service proxy framework that utilizes the service provided meta-data and introspection capabilities of grid services.